BAGHDAD, Iraq, July 16 — As sectarian violence soars, many Sunni Arab political and religious leaders once staunchly opposed to the American presence here are now saying they need American troops to protect them from the rampages of Shiite militias and Shiite-run government forces.

The pleas from the Sunni Arab leaders have been growing in intensity since an eruption of sectarian bloodletting in February, but they have reached a new pitch in recent days as Shiite militiamen have brazenly shot dead groups of Sunni civilians in broad daylight in Baghdad and other mixed areas of central Iraq.

The Sunnis also view the Americans as a “bulwark against Iranian actions here,” a senior American diplomat said. Sunni politicians have made their viewpoints known to the Americans through informal discussions in recent weeks.

The Sunni Arab leaders say they have no newfound love for the Americans. Many say they still sympathize with the insurgency and despise the Bush administration and the fact that the invasion has helped strengthen the power of neighboring Iran, which backs the ruling Shiite parties.

But the Sunni leaders have dropped demands for a quick withdrawal of American troops. Many now ask for little more than a timetable. A few Sunni leaders even say they want more American soldiers on the ground to help contain the widening chaos.

The new stance is one of the most significant shifts in attitude since the war began.